The stopping potential ( ) is a measure of the maximum kinetic energy ( ) of the emitted photoelectrons, related by .
Therefore, . This shows that the stopping potential is related to the work function and the incident frequency, but it is not a direct measure of the work function.
According to the quantum explanation of the photoelectric effect, the interaction between a photon and an electron is instantaneous.
From Einstein's photoelectric equation,

This equation shows a linear relationship between the stopping potential ( ) and the frequency ( ) of the incident radiation, with a slope of h/e.
The work function ( ) is an intrinsic property of the metal and it is independent of the intensity or frequency of the incident light.
The intensity of light is directly proportional to the number of photons incident per unit time.
Therefore, increasing the number of incident photons (by increasing intensity) will lead to an increase in the number of photoelectrons emitted per second.